Amino acids nutrition

Twenty amino acids are the building blocks of proteins (Table 1). Some of them can not be synthesised, or not in sufficient quantities, by animals; they must therefore be supplied through the feed and are referred to as indispensable amino acids. The indispensable amino acids could differ depending on the species (Table 2). To maintain good health and growth performance, feeds must provide the indispensable amino acids in sufficient quantities to cover the requirement of animals.

Amino acid

3-letter

Amino acid

3-letter

Alanine

Ala

Leucine

Leu

Arginine

Arg

Lysine

Lys

Asparagine

Asn

Methionine

Met

Aspartic acid

Asp

Phenylalanine

Phe

Cysteine

Cys

Proline

Pro

Glutamic acid

Glu

Serine

Ser

Glutamine

Gln

Threonine

Thr

Glycine

Gly

Tryptophan

Trp

Histidine

His

Tyrosine

Tyr

Isoleucine

Ile

Valine

Val

Table 1. The 20 amino acids encoded directly by the genetic code and their 3-letter abbreviations

Essential amino acids (EAA)

Amino acids involved in the biological functions that are necessary for life supplied through the diet or synthesised de novo by animals.

Pigs

Broiler

• Indispensable amino acids

EAA that can not be synthesised de novo or at a sufficient rate to maintain the associated biological functions

Lys

Lys

Thr

Thr

Met

Met

Trp

Trp

Val

Val

Ile

Ile

Leu

Leu

His

His

Phe

Phe

Arg

• Dispensable amino acids

Conditionally or semi-dispensable amino acids

EAA that can be synthesised de novo but that could become indispensable in specific situations when the synthesis become not sufficient to cover the requirement

Cys

Cys

Tyr

Tyr

Arg

Strictly dispensable amino acids

EAA that can be synthesised de novo by animals in a sufficient rate in any cases

Glu, Gln, Gly, Ser, Pro, Asp, Asn, Ala

Table 2. Classification of the 20 amino acids encoded directly by the genetic code, for pigs and broiler